From: Shawn O. Pearce <spearce@spearce.org>
Date: Mon, 19 Jan 2009 17:51:54 GMT
Subject: Re: [JGIT PATCH 8/8] Define a basic merge API, and a two-way tree merge strategy
Message-ID: <20090119175154.GD14053@spearce.org>
In-Reply-To: <20090119174254.GC14053@spearce.org>

"Shawn O. Pearce" <spearce@spearce.org> wrote:
> Tomi Pakarinen <tomi.pakarinen@gmail.com> wrote:
> > testTrivialTwoWay_disjointhistories() failed because merge strategy
> > didn't handle missing base
> > version. Am'i right?
> 
> If that isn't coming out right then perhaps tw.idEqual() is busted

Yup, that's what it is, idEqual is busted.

The definition of TreeWalk.idEqual is:

	public boolean idEqual(final int nthA, final int nthB) {
		final AbstractTreeIterator ch = currentHead;
		final AbstractTreeIterator a = trees[nthA];
		final AbstractTreeIterator b = trees[nthB];
		return a.matches == ch && b.matches == ch && a.idEqual(b);
	}

The problem is this method always returns false if the name isn't
defined in either path.  I think this is the definition we want
instead:

		if (a.matches == ch && b.matches == ch)
			return a.idEqual(b);
		if (a.matches != ch && b.matches != ch) {
			// If neither tree matches the current path node then neither
			// tree has this entry. In such case the ObjectId is zero(),
			// and zero() is always equal to zero().
			//
			return true;
		}
		return false;

Patch to follow.

-- 
Shawn.